The present invention relates to nuclear system Boiling Water Reactor (BWR) containments and, refers more particularly to such a reactor containment in which a suppression pool wetwell space is continuously ventilated, as well as a method for ventilating such containment, to remove non-condensable gases from the wetwell space so that during a loss-of-coolant-accident, drywell space pressure can be maintained at not above about one atmosphere gauge pressure thereby allowing use of lighter weight containment structures, as well as enclosure of more components within the containment.
Nuclear system nuclear reactors are housed in containment enclosures as accident mitigation structures. These structures generally are designed as high pressure buildings surrounding the reactor system to function to contain all fluid and fission products which release upon occurrence of a reactor loss-of-coolant-accident (LOCA). Efforts to improve these containment designs have been ongoing and in recent years system improvements proposed include, inter alia, addition of a high-pressure relief line with a filter system to trap particulate fission products as non-condensable gases are released to relieve pressure. Still, all past containment designs require a high pressure enclosure around the reactor system to collect the energy, fluids and fission products released incident a LOCA. These containment buildings in turn require isolation systems for process lines and penetrations through the containment boundary, and they are complex and expensive mandating use of as compact a structure as possible.